Cruise Engine On; Powerplant Extension-Retraction In Flight - DG Flugzeugbau DG-1000 Flight Manual

4.5.3

Cruise engine on

4.5.3.1 General
The engine of the DG-1000T is not designed for continuous cruise with the
engine. Due to the drag of the extended powerplant and as the propeller is
designed for optimum climb performance, cruise with higher speed is not
efficient.
The optimum cruise is with the so called sawtooth technique. After climb with
Vy retract the engine and glide with airspeed according to the Mc Cready
theory, flying slowly in lift and faster in sinking air.
The medium cruise speed achieved by sawtooth technique is not much less than
for level engine on cruise, but the range will be 1.5 times longer.
Performance data see sect. 5.3.5.
Warning: if there is a problem with the elastic damper element of the propeller
adapter, the power plant may oscillate around its vertical axis with low
frequency (1-10 Hz). If such oscillations start, switch off the ignition
immediately. Report to DG Flugzeugbau prior to next engine use.
4.5.4

Powerplant extension-retraction in flight

4.5.4.1 Extension and starting the engine in flight
1. With the engine extended but not running the rate of sink at 90 km/h (49
kts) increases to 1.5 m/sec. (300 ft/min.).
Therefore restarting the engine should only be done over landable terrain
and not below 400 m (1320 ft) above ground. But it is better to restart the
engine at 200 m (660 ft) over a landable field rather than at 400 m (1320 ft)
over a forest or unlandable scrub.
Should a flight be conducted over a wide expanse of unlandable terrain, the
engine should then be restarted at 1000 m (3300 ft) above ground level so
that if the engine does not start, all the emergency starting procedures can
be followed unhurriedly including retraction of the engine if necessary.
2. In a normal restarting situation the loss of altitude from starting the
extension procedure until the engine is running is only about 20 m (70 ft).
3. Extension: Fly at 80-90 km/h (43-49 kts). Check if the primer switch is in
the "auto" position and if the fuel cock is open.
Throttle on idle, switch on the ignition. The engine will extend by itself.
You may press the starter button before the engine is extended completely.
The starter motor will start the engine as soon as the powerplant is
extended.
When the engine fires, release the starter button and move the throttle
slowly to full throttle.
In case of starting problems see sect. 4.5.4.3.
Warning: If after starting the engine the failure message "Starter Run" will be
displayed, the starter motor didn't disengage and produces electric power, stop
the engine immediately to prevent damage of the electrical system.
Issued: August 2015
Flight manual DG-1000T
TM 1000/26 EASA app.
4.14